CN108144592B - Superparamagnetic composite nanoparticle, preparation method thereof and method for efficiently and selectively recovering phosphate - Google Patents

Superparamagnetic composite nanoparticle, preparation method thereof and method for efficiently and selectively recovering phosphate Download PDF

Info

Publication number
CN108144592B
CN108144592B CN201711234252.0A CN201711234252A CN108144592B CN 108144592 B CN108144592 B CN 108144592B CN 201711234252 A CN201711234252 A CN 201711234252A CN 108144592 B CN108144592 B CN 108144592B
Authority
CN
China
Prior art keywords
particles
phosphate
water
composite
zirconium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201711234252.0A
Other languages
Chinese (zh)
Other versions
CN108144592A (en
Inventor
劳敏慈
方利平
吴百乐
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hong Kong University of Science and Technology HKUST
Original Assignee
Hong Kong University of Science and Technology HKUST
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hong Kong University of Science and Technology HKUST filed Critical Hong Kong University of Science and Technology HKUST
Publication of CN108144592A publication Critical patent/CN108144592A/en
Application granted granted Critical
Publication of CN108144592B publication Critical patent/CN108144592B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28009—Magnetic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28016—Particle form
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28057—Surface area, e.g. B.E.T specific surface area
    • B01J20/28061—Surface area, e.g. B.E.T specific surface area being in the range 100-500 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/18—PO4-P
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Nanotechnology (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Water Supply & Treatment (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Materials Engineering (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Water Treatment By Sorption (AREA)

Abstract

The invention relates to a superparamagnetic composite nanoparticle, a preparation method thereof and a method for efficiently and selectively recovering phosphate. The composite nanoparticle includes a superparamagnetic material particle as a core, and a zirconia outer shell directly coated on the core. The preparation method of the composite nano-particles comprises the following steps: dispersing particles of a superparamagnetic material and zirconium (IV) alkyl alcohol in absolute ethanol to form a mixture; and adding water to the mixture to cause controlled hydrolysis of the zirconium (IV) alkyl alcohol to form a zirconium oxide shell coating directly on the particles of superparamagnetic material. The composite nano-particles can be used for efficiently and selectively recovering phosphate from treated water.

Description

Superparamagnetic composite nanoparticle, preparation method thereof and method for efficiently and selectively recovering phosphate
Technical Field
The invention relates to a water treatment technology. In particular, the present invention relates to a superparamagnetic composite nanoparticle, a method for preparing the same, and a method for efficiently and selectively recovering phosphate from treated water using the composite nanoparticle.
Background
Phosphorus is widely used as an important raw material in agriculture and industry. Phosphorus is present in water primarily in the form of phosphate. Excess phosphorus is discharged into surface water in large quantities through sewage discharge and agricultural runoff, resulting in eutrophication of the water body. Strict regulations have been issued in some countries around the world in an attempt to control the phosphorus content in natural water bodies to be below 0.02mg/L and the phosphorus content in sewage to be below 0.5 mg/L. Meanwhile, phosphorus is also a non-renewable resource, and if the demand of human beings for phosphate fertilizers continues to increase, the remaining mined phosphate ore can only be maintained for 50 years. Therefore, in order to alleviate the contradiction between the eutrophication problem of water and the gradual shortage of phosphorus resources, the invention of an advanced technology for removing and recovering phosphate in water is urgently needed.
At present, the method for removing phosphorus in water mainly comprises the following steps: chemical precipitation, biological, and adsorption. The adsorption method is easy to design, operate and low in cost, so that the adsorption method is known as an effective method for removing phosphorus from sewage. The key point of the adsorption method is to search for a proper adsorbent, and currently, phosphorus removal adsorbents commonly used in water treatment comprise activated carbon, resin and the like. However, the water to be dephosphorized may contain various competitive ions, and the following disadvantages limit the practical application of these adsorbents: (1) no selectivity and low adsorption capacity; (2) the adsorbent is difficult to desorb, so that the reusability is poor; (3) the recovery of the adsorbent after water treatment is difficult.
Mixing superparamagnetic material (such as ferroferric oxide, Fe)3O4) The magnetic adsorbent with the core-shell structure formed by combining the particles and the adsorbing material has great application potential in the field of water purification. In the prior art, when a magnetic adsorbent material with a core-shell structure is prepared, the surface of a superparamagnetic material particle is coated in advanceA non-magnetic protective layer (such as an oxidation-resistant layer) is coated on the adsorbing material. For example, mixing Fe3O4The pre-coating of the core with a layer of silica is a common Fe-preventing coating3O4By oxidation followed by precipitation (e.g. by bringing ZrOCl2Hydrolyzed in a mixed solution of concentrated ammonia and ethanol) to deposit zirconia on the silica layer. However, the inventors have found that pre-coating a non-magnetic protective layer (e.g. a silica layer) results in a significant reduction in the magnetic properties of the adsorbent, which leads to difficult separation of the adsorbent and ultimately to prolonged magnetic separation times. In addition, owing to the rapid uncontrolled hydrolysis of the zirconium salts during the precipitation process, larger ZrO deposits can form which accumulate in the wrong place2The agglomerates result in a non-uniform, discontinuous zirconia layer being formed, such that the sorbent surface is not completely covered by the zirconia layer, and the zirconia layer has undulating surface and widely fluctuating thickness. In addition, when the adsorbent is regenerated using a strong base (e.g., NaOH), the zirconia layer is not continuous and does not completely cover the surface of the adsorbent, which may cause the underlying silica layer to dissolve, destroy the structure of the adsorbent, and cause Fe3O4The nuclei are oxidized, which further affects the reusability of the adsorbent.
Disclosure of Invention
In order to solve one or more of the above problems, the present invention provides a superparamagnetic composite nanoparticle having a core-shell structure, the composite nanoparticle including a superparamagnetic material particle as a core, and a zirconia outer shell directly coated on the core.
The invention also provides a method for preparing the superparamagnetic composite nano-particles with the core-shell structures, which comprises the following steps: dispersing particles of a superparamagnetic material and zirconium (IV) alkyl alcohol in absolute ethanol to form a mixture; and adding water to the mixture to cause controlled hydrolysis of the zirconium (IV) alkyl alcohol to form a zirconium oxide shell coating directly on the particles of superparamagnetic material.
By the method for controlled hydrolysis of zirconium (IV) alkyl alcohol, zirconium oxide can be directly and uniformly loaded on the surface of a superparamagnetic material particle serving as a core, so that the core-shell composite nanoparticle with a zirconium oxide shell layer directly coated on the core is obtained. The inventors have surprisingly found that the composite nanoparticles of the invention have a significantly improved specific surface area and zirconium loading compared to prior art composite particles in which the surface of the core is pre-deposited with silica, and therefore promote the adsorption of phosphate in water; in addition, the composite nano-particles of the present invention also have stronger magnetization, thereby facilitating the separation of phosphate from water using magnetic force after adsorbing the phosphate. The composite nano-particle has superparamagnetism, has high selectivity on phosphate, can efficiently and selectively recover the phosphate under the condition that competitive anions with high concentration exist in water, can resist strong alkali, and has high chemical stability and magnetic stability, so the composite nano-particle can be repeatedly used. The composite nanoparticles of the present invention are therefore particularly suitable as adsorbents for the recovery of phosphate from treated water, including natural water and sewage. The composite nano-particles can be used as an adsorbent, can quickly and selectively adsorb phosphate from water, can be easily separated from water after adsorption, and finally desorbs the phosphate from the adsorbent in strong alkali to obtain high phosphate recovery rate, and can be recycled during regeneration of the adsorbent. The recovery of phosphate from water using the composite nanoparticles of the present invention has outstanding economic and environmental advantages. The invention has important significance for controlling water eutrophication and recovering phosphate resources.
Drawings
FIG. 1 is a diagram of the synthesis of ZrO having a core-shell structure in one exemplary embodiment2-Fe3O4Superparamagnetic composite nanoparticles (denoted as ZrO)2@Fe3O4) A schematic flow chart of (a);
FIG. 2 shows Fe synthesized in preparation example3O4(a)、SiO2@Fe3O4(b)、ZrO2@SiO2@Fe3O4Particles I (c) and II (d), and ZrO2@Fe3O4Transmission electron display of particles (e)Micro-mirror photograph (scale: 200nm), ZrO2@Fe3O4Elemental surface scan profiles (f) of the particles (blue in the elemental surface scan profiles representing zirconium, orange in the elemental surface scan profiles representing iron), and Vibration Sample Magnetometer (VSM) analysis results (g) of the respective particles;
FIG. 3 schematically shows ZrO2@Fe3O4An adsorption-magnetic separation-desorption process for recovering phosphate from natural water and sewage (collectively referred to as sewage);
FIG. 4 shows ZrO synthesized by preparation example2@Fe3O4、ZrO2@SiO2@Fe3O4Particles I and pure Fe3O4Phosphate adsorption kinetics at pH 7.0;
FIG. 5 shows ZrO synthesized by preparation example2@Fe3O4、ZrO2@SiO2@Fe3O4Particles I and pure Fe3O4Phosphate adsorption isotherms at pH 7.0;
FIG. 6 shows the use of ZrO in contaminated water synthesized with deionized water and actual contaminated water2@Fe3O4The experimental results of removing and recovering phosphate are 5 times of circulation. The experimental conditions are as follows: ZrO (ZrO)2@Fe3O4Adding amount: 0.5 g/L; initial phosphate concentration: 2.0mg P/L of synthetic sewage, 1.9mg P/L of actual sewage sample, desorption solution: 1M NaOH, volume ratio of adsorption solution/desorption solution: 10: 1;
FIG. 7 shows competitive anion and humic acid vs. ZrO2@Fe3O4The effect of adsorbing phosphate. The number (e.g., 1:1) is the molar ratio of phosphate to other anion concentrations. The experimental conditions are as follows: ZrO (ZrO)2@Fe3O4Adding amount: 0.5g/L, initial phosphate concentration: 2.0mg P/L, pH 7.0;
FIG. 8 shows the newly synthesized ZrO2@Fe3O4And its magnetization after undergoing 1 or 5 adsorption/desorption cycles.
Detailed Description
In order that those skilled in the art will better understand the present invention, a more detailed description is provided below with reference to specific embodiments and the accompanying drawings, but the present invention is not limited thereto.
The invention provides a superparamagnetic composite nanoparticle with a core-shell structure, which comprises superparamagnetic material particles serving as a core and a zirconia outer shell layer directly coated on the core.
The term "direct coating" means that zirconia is directly deposited on the particles of superparamagnetic material (e.g. Fe) as a core3O4) So that there is no other non-magnetic material layer (e.g. SiO) between the zirconia outer shell layer and the core2Layers).
The zirconia outer shell layer is preferably continuous. In other words, the zirconia outer shell layer has no voids, and thus the surface of the superparamagnetic material particle as a core is completely coated with zirconia.
The thickness of the zirconia outer shell layer is preferably substantially uniform. Fluctuation of thickness of the outer shell layer
Figure BDA0001488714190000041
To (where d is the skin thickness d at any location,
Figure BDA0001488714190000042
average thickness of the outer shell layer), the thickness variation may be an average thickness of the outer shell layer
Figure BDA0001488714190000043
Within + -5%, even within + -4%, + -3%, + -2% or + -1%.
Average thickness of zirconia outer shell layer
Figure BDA0001488714190000044
May be in the range of 25-35nm, e.g. 27, 29, 31, 33nm, preferably 30 nm.
The composite nanoparticles of the present invention can have significantly improved zirconium loading compared to prior art composite particles having silica pre-deposited on the surface of the core. The mass of zirconium in the zirconia outer shell layer of the present invention can comprise 23% to 30% of the total mass of the composite nanoparticle, for example 25%, 26.7%, 27%, 29%.
The superparamagnetic material particle may be selected from ferroferric oxide and gamma-ferric oxide. For example, the superparamagnetic material particles may for example be ferroferric oxide particles prepared by a conventional solvothermal process, preferably ferroferric oxide particles prepared from ferric chloride (e.g. ferric chloride hexahydrate) in ethylene glycol in the presence of sodium citrate and sodium acetate by a solvothermal process. Among them, the molar ratio of ferric chloride hexahydrate, sodium citrate and sodium acetate is preferably in the range of 1.5:0.25:6.5 to 2.5:0.35:7.5, for example, 2:0.3: 7.
The mean particle size of the particles of superparamagnetic material may be in the range of 180-250nm, for example 190, 200, 210, 220, 230 or 240nm, preferably 200 nm. The specific surface area of the superparamagnetic material particles can be 80-100m2In the range of/g, for example 85, 87, 89.2, 90, 92, 95 or 97m2(ii) in terms of/g. The saturation magnetization of the particles of the superparamagnetic material is preferably in the range of 55-75emu/g, for example 60, 63, 65.7, 67, 70 or 72 emu/g. The particles of superparamagnetic material may be monodisperse.
The present invention has surprisingly found that core-shell superparamagnetic composite nanoparticles with excellent properties are obtained despite the absence of the normally required pre-coated non-magnetic material layer (protective layer such as silica). The composite nanoparticles of the present invention can have significantly increased specific surface area compared to prior art composite particles in which the surface of the core is pre-deposited with silica. The specific surface area of the composite nano-particles can be 125-145m2In the range of/g, for example 130, 135, 135.8, 137, 140 or 142m2(ii) in terms of/g. The composite nanoparticles of the present invention may have a stronger magnetization than prior art composite particles in which silica is pre-deposited on the surface of the core. The saturation magnetization of the composite nanoparticles of the present invention may range from 20 to 40emu/g, such as 25, 27, 30.5, 32, 35, or 38 emu/g.
The composite nano-particles have good adsorption capacity on phosphate in water, and the adsorption capacity on the phosphate can be more than 15mg P/g; and/or the adsorption rate constant for phosphate may be 1.5 g/(mg. min) or more.
The composite nano-particles can tolerate strong alkali and have high chemical stability and magnetic stability, so the composite nano-particles have good reusability. When the composite nano-particles are repeatedly used for recovering phosphate in water through an adsorption/desorption cycle process, after 5 times of adsorption/desorption cycle processes, the saturation magnetization can be kept above 96% of the saturation magnetization before the composite nano-particles are used; and/or the zirconium content may be maintained above 97% of the zirconium content prior to its use; and/or the recovery of phosphate during the 5 th adsorption/desorption cycle may be maintained above 95% of the recovery of phosphate during the 1 st adsorption/desorption cycle. This is a good indication that the composite nanoparticles of the present invention exhibit excellent chemical and magnetic stability despite the absence of a pre-coated non-magnetic material layer (protective layer such as silica) as is typically required.
The present invention also provides a method for preparing composite nanoparticles, comprising the steps of: dispersing particles of a superparamagnetic material and zirconium (IV) alkyl alcohol in absolute ethanol to form a mixture; and adding water to the mixture to cause controlled hydrolysis of the zirconium (IV) alkyl alcohol to form a zirconium oxide shell coating directly on the particles of superparamagnetic material.
The term "controlled hydrolysis" means that the rate of hydrolysis is controlled by controlling the amount of water added and the reaction temperature so that it proceeds gently and slowly. More specifically, the hydrolysis temperature may be controlled at a temperature of 50-70 ℃ (e.g., 55, 57, 60, 62, 65, 67 ℃), and the volume ratio of the amount of water added to the mixture to the absolute ethanol may be controlled in the range of 1:350 to 1:450 (e.g., 1:370, 1:380, 1:390, 1:400, 1:410, 1:420, 1:430, 1: 440).
The zirconium (IV) alkyl alcohol can be selected from zirconium butanol and zirconium propanol. The water added to the mixture is preferably deionized water. The mass ratio of zirconium (IV) alkyl alcohol to the particles of superparamagnetic material is preferably in the range of 3:1 to 4:1, e.g. 3.3:1, 3.5:1, 3.7: 1.
The invention also provides a method of treating water containing phosphate comprising contacting any of the composite nanoparticles according to the invention with water containing phosphate to adsorb phosphate from the water. By the water treatment method, the removal rate of phosphate in water can reach more than 99%. The water to be treated may be, for example, natural water or sewage water. In addition to phosphate ions, the water being treated may also contain other competing anions, such as chloride, nitrate, sulfate, bicarbonate, or may also contain humic acid. The presence of these competing anions or humic acids does not substantially affect the adsorption of phosphate by the composite nanoparticles of the invention, and therefore the process has a high selectivity. The method may further include a separation step in which the phosphate-adsorbed composite nanoparticles are separated from water and a desorption step, which are performed after the adsorption step; in the desorption step, the separated composite nanoparticles are desorbed to recover phosphate and regenerate the composite nanoparticles. The composite nano-particles of the invention have superparamagnetism and can be separated by magnetic force. The desorption step may be carried out in a strong alkaline solution, preferably sodium hydroxide solution. The concentration of the strong base solution may generally be in the range of 0.1 to 1 mole per liter (M). By the water treatment method, the recovery rate of the phosphate in the water can reach more than 88 percent.
Hereinafter, ZrO with a core-shell structure2-Fe3O4Superparamagnetic composite nanoparticles (denoted as ZrO)2@Fe3O4) The present invention will be described in more detail for the purpose of example. In one embodiment, as shown in FIG. 1, monodisperse Fe is prepared by a solvothermal method3O4Microspheres, followed by controlled hydrolysis of zirconium (IV) butanolate (modified sol-gel method) in the presence of monodisperse Fe3O4The surface is directly and uniformly loaded with zirconia, thereby obtaining ZrO2@Fe3O4A composite nanoparticle material. Fe3O4Can be prepared as follows: mixing ferric chloride hexahydrate, sodium citrate and sodium acetate in ethylene glycol to uniformity, sealing the obtained mixture in autoclave (such as with polytetrafluoroethylene)A stainless steel autoclave with an internal bladder) under heating (e.g., 200 ℃) to completion (e.g., about 10 hours). After cooling to room temperature, the resulting black product is washed (e.g., three times with ethanol and deionized water, respectively), and then collected under a magnetic field. The optimum molar ratio of ferric chloride hexahydrate, sodium citrate and sodium acetate is in the range 1.5:0.25: 6.5-2.5: 0.35:7.5, preferably 2:0.3: 7. In Fe3O4Upper cladding ZrO2This can be achieved by slow hydrolysis of zirconium (IV) n-butoxide in ethanol containing a small amount of water. The surface coating process comprises the following steps: mixing Fe3O4And zirconium n-butoxide in absolute ethanol until homogeneous (e.g., stirring at 60 ℃ for 30 minutes); to the resulting mixture, a small amount (e.g., 1:400 by volume with absolute ethanol) of deionized water is added to allow controlled hydrolysis of zirconium n-butoxide (e.g., 5 hours at 60 ℃). The product is collected and washed (for example, it may be washed three times using ethanol and deionized water, respectively) to obtain ZrO having a core-shell structure2@Fe3O4Composite materials, as shown in (e) and (f) of fig. 2.
As indicated by a Vibrating Sample Magnetometer (VSM) test ((g) in FIG. 2), the ZrO2@Fe3O4The composite material has superparamagnetism. As shown by adsorption/desorption experiments (FIGS. 3 to 8), the ZrO2@Fe3O4The composite material can rapidly and selectively remove and recover phosphate from natural water and sewage, can easily separate the adsorbent from the water after adsorption, and finally can desorb the phosphate in strong alkali to obtain high phosphate recovery rate, thereby providing a material capable of economically and environmentally recovering the phosphate.
The technical features of the various aspects and embodiments of the present invention may be combined with each other. As used in the specification and claims of this application, the articles "a," "an," "the," and "the" preceding a noun include more than one of the referenced item unless the content clearly dictates otherwise. The term "and/or" means that the alternatives can be selected simultaneously or that only any one of the alternatives can be selected. The operations referred to in this invention are carried out at ambient temperature, unless otherwise indicated. Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical characteristics used herein are to be understood as being modified in all instances by the term "about". Further, the recitation of numerical ranges by endpoints includes the endpoints, and all sub-ranges and values within that range (e.g., 0 to 5 includes 0, 1, 2, 3, 4, 5, 1.5-3).
The present invention will be further explained or illustrated by the following examples, which should not be construed as limiting the scope of the present invention.
Examples
Unless otherwise specified, all chemical reagents used in the following examples are analytically pure. ZrOCl2·8H2O (99.5%) and n-butanol zirconium (IV) solution (solvent n-butanol, concentration 80 wt%) were purchased from Sigma-Aldrich, USA. Deionized water was used to formulate the solutions unless otherwise specified. Mixing KH with water2PO4Dissolved in deionized water to prepare a phosphate stock solution (100mg P/L).
Analytical test method
TEM: the morphology of the material was studied using a transmission electron microscope (TEM-EDS, JEM-2010 from JEOL, Japan) coupled to an energy dispersive X-ray spectrometer at an acceleration voltage of 20 kV.
VSM: the magnetic properties of the material were analyzed by vibrating a sample magnetometer (VSM, Lake Shore 7037, usa) at room temperature.
Specific surface area: specific surface area measurement was carried out by the Brunauer-Emmett-Teller (BET) method on a surface area analyzer (NOVA-3200 e of Quantachrome, U.S.A.). Prior to analysis, the samples were degassed at 80 ℃ for 24 hours.
Zirconium content (i.e., the mass of zirconium in the outer shell layer as a percentage of the total mass of the composite nanoparticle, also referred to as zirconium loading): measured using an inductively coupled plasma emission spectrometer (ICP-OES, Optima 7300DV from Perkin-Elmer, USA).
Adsorption rate constant: q is calculated byt＝k2qe 2t/(1+k2qt) Wherein q ist(mg P/g) is the amount of phosphate adsorbed at time t (min), k2(g/(mg. min)) is a pseudo-second order adsorption rate constant, qe(mg P/g) represents the amount of adsorbed phosphate at equilibrium.
Adsorption capacity: q is calculated bye＝qmaxKLCe/(1+KLCe) Wherein q ise(mg P/g) is the phosphate adsorption at equilibrium, Ce(mg P/L) is phosphate concentration at equilibrium, KL(L/mg) is Langmuir constant, qmax(mg P/g) is the maximum phosphate adsorption (i.e., adsorption capacity).
Removal rate of phosphate [ (P)0-P1)/P0]X 100% where P0Represents the phosphate concentration, P, in the water before treatment with the composite nanoparticles1Indicates the phosphate concentration in the water after treatment with the composite nanoparticles.
Recovery of phosphate [ P ]2V2/(P0-P1)V0]X 100% where P0、P1As defined above, P2Denotes the phosphate concentration, V, in the desorption solution obtained after desorption of the phosphate-adsorbed composite nanoparticles0Volume of water treated, V2Is the volume of the desorption solution.
Adsorption kinetics experiment: the adsorption kinetics test of the particles for phosphate was performed by mixing 0.025g of the prepared composite nanoparticles with 50ml of 2.0mg of P/L phosphate solution. The solution was maintained at pH 7.0. + -. 0.1 and shaken at 200 rpm. Samples were taken periodically for phosphate concentration analysis. Each experiment was repeated three times.
Adsorption isotherm experiments: 0.01g of the prepared composite nanoparticles were suspended in 20mL of deionized water at an initial phosphate concentration of 0.5-8mg P/L (for ZrO)2@SiO2@Fe3O4) Or 0.5-13mg P/L (for ZrO)2@Fe3O4). The solution was maintained at pH 7.0. + -. 0.1 and shaken at 200 rpm. Each experiment was repeated three times.
The analysis method comprises the following steps: the phosphate concentration was determined by the ammonium molybdate method on a UV/visible spectrophotometer (Lambda 25 from Perkin-Elmer, USA). The concentration of background anions was determined by ion chromatography (HIC-20A Super, Shimadzu, Japan). The Total Organic Carbon (TOC) of the sewage sample was analyzed using a TOC analyzer (TOC analyzer of Shimadzu corporation, japan).
Preparation example 1
Preparation of Fe by solvothermal method3O4And (3) nanoparticles. Ferric chloride hexahydrate (2.16g) and sodium citrate (0.40g) were first dissolved in ethylene glycol (40mL) while mixing with sodium acetate (2.40g) under magnetic stirring. The mixture was then stirred for a further 1 hour and subsequently sealed in a stainless steel autoclave with a teflon inner liner. The autoclave was heated at 200 ℃ for 10 hours and then cooled to room temperature. Washing the obtained black product with ethanol and deionized water for three times respectively, and collecting the black product under a magnetic field to obtain Fe3O4And (3) granules. By Transmission Electron Microscope (TEM) (FIG. 2 (a)), Fe3O4The particle microsphere has good monodispersity, the particle size is about 200nm, and the specific surface area is 89.2m2G, which facilitates further ZrO coating on the surface thereof2。
Preparation example 2
In Fe synthesized according to preparation example 13O4ZrO by slow hydrolysis of zirconium (IV) n-butoxide in ethanol with a small amount of water in the presence of particles2Cladding to obtain ZrO with a core-shell structure2@Fe3O4And (3) granules. The surface coating process comprises the following steps: 0.5g of said Fe is mixed by mechanical stirring3O4The particles are dispersed in 200mL of absolute ethyl alcohol; adding 2mL of n-butyl alcohol zirconium solution into the dispersion and stirring for 30 minutes at 60 ℃; deionized water was added at a volume ratio of 1:400 (i.e., 0.5mL) to absolute ethanol and stirring was continued at 60 ℃ for 5 hours. After the product is collected, the product is respectively washed three times by using ethanol and deionized water, and finally the ZrO with the core-shell structure is obtained2@Fe3O4Composite nano-particle material, ZrO2Is uniformly deposited on Fe3O4On the surface, a continuous shell layer is formed, the following Fe3O4The particles are completely coated as shown in (e) of fig. 2.
ZrO prepared by Vibratory Sample Magnetometer (VSM) testing2@Fe3O4Has superparamagnetism and saturation magnetization of up to 30.5emu/g ((g) in FIG. 2). Both of these characteristics are advantageous for ZrO2@Fe3O4Magnetic separation in water treatment processes. Superparamagnetism of ZrO2@Fe3O4Can be well redispersed in aqueous media without agglomeration or hysteresis, and a high magnetization enables ZrO2@Fe3O4Separating rapidly at lower magnetic force.
Preparation example 3
Preparation of SiO in core-shell structure by sol-gel method2@Fe3O4And (3) granules. 0.5g of Fe synthesized according to preparation example 13O4The nanoparticles were dispersed in 200mL ethanol (95%) solution and sonicated for 10 min. A mixture of concentrated aqueous ammonia (10mL, 28% by mass) and deionized water (18mL) was added to the dispersion. After stirring for 30 minutes, 1mL of tetraethyl orthosilicate (TEOS) was quickly injected and the reaction was continued for 4 hours. After magnetic separation and washing several times with ethanol and deionized water, SiO is obtained2@Fe3O4And (3) nanoparticles. Observed by a Transmission Electron Microscope (TEM) (FIG. 2 (b)), the surface thereof was smooth, and SiO2The thickness is about 30 nm.
Preparation of ZrO by modified sol-gel process (controlled hydrolysis of zirconium n-butoxide)2@SiO2@Fe3O4And (3) particles I. 0.8g of SiO prepared as described above2@Fe3O4Dispersed in 200mL of absolute ethanol. To the resulting suspension was added 2mL of zirconium n-butanol and mechanically stirred at 60 ℃ for 30 minutes. Then 0.5mL of deionized water was injected to initiate hydrolysis. After stirring at 60 ℃ for 5 hours, the mixture was collected with a magnet and washed three times with deionized water and ethanol to obtain ZrO2@SiO2@Fe3O4The Transmission Electron Microscope (TEM) observation result of the particle I is shown in (c) of fig. 2.
In contrast, it is prepared by conventional precipitation methodsZrO2@SiO2@Fe3O4And (II) particles. 0.8g of SiO prepared as described above2@Fe3O4The nanoparticles were dispersed in a mixed solution containing 80mL of deionized water, 1.5mL of concentrated ammonia (28%) and 60mL of ethanol (95%). The resulting mixture was stirred at room temperature for 30 minutes. Then ZrOCl is dripped2·8H2O solution (0.61g in 2mL ethanol), the resulting mixture was stirred for 6 hours. The product was collected by magnetic separation and washed three times with water and ethanol, respectively, to obtain ZrO2@SiO2@Fe3O4And (II) particles.
The ZrO prepared by the precipitation method was found by observation with a Transmission Electron Microscope (TEM)2@SiO2@Fe3O4Particle II showed poor inhomogeneous ZrO2Surface of the layer (d in FIG. 2), secondary particles and large ZrO are formed due to rapid uncontrolled hydrolysis of zirconium salts in the aqueous phase in this process2Agglomerates which are discontinuously distributed on the surface of the composite particles so that ZrO-free regions are present on the surface of the particles2A bare area of coverage, which can adversely affect the performance of adsorptive phosphate removal and its reusability.
The results of the measurements of the specific surface area, the zirconium content, and the saturation magnetization value of the particles obtained in each preparation example are shown in table 1 below.
TABLE 1 BET specific surface area, zirconium content and saturation magnetization of different particles
Figure BDA0001488714190000111
As shown by the test results in Table 1, SiO2Layer of Fe3O4The surface area of the particles was from 89.2m2The/g is reduced to 9.6m2(ii) in terms of/g. This in turn has a significant influence on ZrO2@SiO2@Fe3O4Surface area of the particles (17.1 m)2In terms of/g). In contrast, ZrO of the present invention2@Fe3O4The particles then have a size of up to 135.8m2Surface area per gram and also a Zr content significantly higher than ZrO2@SiO2@Fe3O4The Zr content of the particles, which favors phosphate adsorption. In addition, ZrO2@Fe3O4The magnetization of the particles is significantly higher than ZrO2@SiO2@Fe3O4Particles, which facilitate magnetic separation of the adsorbed particles.
With the prepared particles, an adsorption/desorption process as shown in fig. 3 was performed. The prepared ZrO2@Fe3O4The composite particles were placed in a phosphate-containing body of water and the mixture was then shaken until the phosphate adsorption reached equilibrium, as shown in FIG. 4, which took about 15 minutes to reach equilibrium, which is comparable to ZrO2@SiO2@Fe3O4The particles (about 60 minutes) are much faster. In addition, ZrO2@Fe3O4The adsorption rate constant of the particles is 1.75 g/(mg. min), which is much higher than that of ZrO2@SiO2@Fe3O4Adsorption rate constant of the particles (0.24 g/(mg. min)). Thus, ZrO2@Fe3O4The ability to adsorb phosphate more rapidly is unexpected.
After the phosphate is adsorbed, ZrO is treated by a magnetic field2@Fe3O4Separated from the water and collected. Prepared ZrO2@Fe3O4The adsorption capacity of the composite material to phosphate is 15.91mg P/g when the pH value of the water solution is 7, which is far larger than that of Fe3O4Adsorption amount of (about 5mg P/g) and ZrO2@SiO2@Fe3O4The amount of adsorbed (6.33mg P/g) is shown in FIG. 5. These results show that ZrO used in the present invention2Direct coating of Fe3O4The phosphate adsorption effect can be advantageously improved.
In the desorption process, ZrO already adsorbed with phosphate in the adsorption process is desorbed2@Fe3O4Added to a desorption solution of 1M NaOH for desorption and recovery of phosphate. For phosphate concentration, the volume ratio of desorption solution (NaOH solution) to adsorption solution (treated water) was 1:10, at which a phosphate recovery of up to 82.8% could be obtained (fig. 6). After the recovery of the phosphate, the phosphate is recovered,ZrO obtained anew2@Fe3O4Can be continuously used for recovering phosphate in natural water or sewage. FIG. 6 shows the ZrO prepared2@Fe3O4The phosphate adsorption/desorption properties remained stable after 5 cycles of adsorption/desorption, indicating that ZrO2@Fe3O4Has high reusability in the aspect of recovering phosphate in water bodies. FIG. 7 shows the ZrO prepared2@Fe3O4The phosphate adsorption performance is still stable when the mole ratio of various competitive anions to phosphate is as high as 100:1, and ZrO is shown2@Fe3O4Has high selectivity for phosphate adsorption. FIG. 8 shows ZrO2@Fe3O4The magnetization value of (A) was almost constant after the course of several adsorption/desorption cycles, indicating that the ZrO prepared was2@Fe3O4Has high magnetic stability.
Application example 1
For the ZrO prepared2@Fe3O4The adsorption and recovery experiments of phosphate were carried out on synthetic wastewater containing 3.1mg/L of phosphorus. The synthetic water contained 3.1mg of P/L phosphate, 71mg/L chloride, 120mg/L nitrate and 192mg/L sulfate. ZrO (ZrO)2@Fe3O4The amount of (B) was 0.5g/L, and the pH of the solution was 7.0. After adsorbing phosphate, ZrO is magnetically treated2@Fe3O4And (5) separating. The removal rate of phosphate is 99.5%, and the concentration of the residual phosphate in the synthetic water is 0.01mg P/L, which is obviously lower than the standard threshold value of phosphate in natural water, namely 0.02mg P/L.
Application example 2
Samples of wastewater were taken from local wastewater treatment plants and the water quality parameters are listed in table 2. A certain amount of ZrO2@Fe3O4Putting into sewage with proper volume to enable ZrO2@Fe3O4The addition amount was 0.5 g/L. The mixture was stirred for 1 hour and then ZrO was magnetically treated2@Fe3O4And (5) separating. Finally, the concentration of phosphate in the sewage is lower than 0.02mg P/L, the removal rate is 99.0 percent, and the sewage reaches the same levelPhosphorus content of 0.5mg/L as specified in the discharge standard.
TABLE 2 quality of wastewater parameters
Figure BDA0001488714190000131
Figure BDA0001488714190000141
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention, and these changes and modifications are also within the scope of the invention.

Claims (13)

1. A method for preparing superparamagnetic composite nanoparticles having a core-shell structure, comprising the steps of:
dispersing particles of a superparamagnetic material and zirconium (IV) alkyl alcohol in absolute ethanol to form a mixture; and
adding water to the mixture to hydrolyze the zirconium (IV) alkyl alcohol at a temperature of 50-70 ℃ to form a zirconium oxide shell layer directly coated on the particles of superparamagnetic material, wherein the volume ratio of the amount of water added to the mixture to the absolute ethanol is in the range of 1:350 to 1: 450.
2. The method according to claim 1, wherein the superparamagnetic material particles are ferroferric oxide particles prepared from an iron precursor by a solvothermal method.
3. The method of claim 1 or 2, further having any one or any combination of features selected from:
a) the zirconium (IV) alkyl alcohol is selected from zirconium butanol and zirconium propanol;
b) the water added to the mixture is deionized water;
c) the superparamagnetic material particles are ferroferric oxide particles prepared by ferric chloride in ethylene glycol in the presence of sodium citrate and sodium acetate through a solvothermal method;
d) the mass ratio of the zirconium (IV) alkyl alcohol to the particles of superparamagnetic material is in the range of 3:1 to 4: 1.
4. A superparamagnetic composite nanoparticle having a core-shell structure prepared by the method of any one of claims 1 to 3, wherein said composite nanoparticle comprises a superparamagnetic material particle as a core, and a zirconia outer shell directly coated on said core; wherein the mass of zirconium in the outer shell layer accounts for 23-30% of the total mass of the composite nanoparticle.
5. The composite nanoparticle of claim 4 wherein the outer shell layer is continuous.
6. The composite nanoparticle of claim 4 wherein the outer shell layer fluctuates in thickness
Figure FDA0002696040970000021
Average thickness of the outer shell
Figure FDA0002696040970000022
Within + -5%.
7. The composite nanoparticle of any of claims 4-6, wherein the outer shell layer further has the following characteristics: average thickness of the outer shell layer
Figure FDA0002696040970000023
In the range of 25-35 nm.
8. The composite nanoparticle according to any one of claims 4-6, wherein the superparamagnetic material particles have any one or any combination of features selected from:
a) the superparamagnetic material particles are selected from ferroferric oxide and gamma-ferric oxide;
b) the average particle size of the superparamagnetic material particles is in the range of 180-250 nm;
c) the specific surface area of the superparamagnetic material particles is 80-100m2In the range of/g;
d) the saturation magnetization of the superparamagnetic material particles is in the range of 55-75 emu/g;
e) the particles of superparamagnetic material are monodisperse.
9. The composite nanoparticle of any one of claims 4-6, further having any one or any combination of features selected from the group consisting of:
a) the specific surface area of the composite nano-particles is 125-145m2In the range of/g;
b) the saturation magnetization of the composite nanoparticles is in the range of 20-40 emu/g;
c) the adsorption capacity of the composite nano particles to phosphate is more than 15mg P/g;
d) the adsorption rate constant of the composite nano particles to phosphate is more than 1.5 g/(mg-min);
e) when the composite nano-particles are repeatedly used for recovering phosphate in water through an adsorption/desorption cycle process, the saturation magnetization after 5 times of adsorption/desorption cycle processes is kept to be more than 96% of the saturation magnetization before the composite nano-particles are used;
f) when the composite nano-particles are repeatedly used for recovering phosphate in water through an adsorption/desorption cycle process, the content of zirconium after 5 times of adsorption/desorption cycle processes is kept to be more than 97 percent of the content of zirconium before the composite nano-particles are used;
g) when the composite nano-particles are repeatedly used for recovering the phosphate in the water through the adsorption/desorption cycle process, the recovery rate of the phosphate in the 5 th adsorption/desorption cycle process is kept to be more than 95 percent of the recovery rate of the phosphate in the 1 st adsorption/desorption cycle process.
10. A method of treating phosphate-containing water comprising the steps of: contacting the composite nanoparticle of any one of claims 4-9 with the phosphate-containing water to adsorb phosphate in the water.
11. The method according to claim 10, further comprising a separation step in which the phosphate-adsorbed composite nanoparticles are separated from water and a desorption step, which are performed after the adsorption step; in the desorption step, the separated composite nanoparticles are desorbed to recover phosphate and regenerate the composite nanoparticles.
12. The method of claim 11, further having any one or any combination of features selected from the following:
a) the separation step adopts magnetic force for separation;
b) the desorption step is carried out in a strong alkaline solution;
c) by the method, the removal rate of phosphate in the water reaches more than 99 percent;
d) by the method, the recovery rate of the phosphate in the water reaches over 88 percent.
13. The method of claim 12 wherein the strong base solution is a sodium hydroxide solution.
CN201711234252.0A 2016-12-02 2017-11-30 Superparamagnetic composite nanoparticle, preparation method thereof and method for efficiently and selectively recovering phosphate Active CN108144592B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201662497779P 2016-12-02 2016-12-02
US62/497,779 2016-12-02

Publications (2)

Publication Number Publication Date
CN108144592A CN108144592A (en) 2018-06-12
CN108144592B true CN108144592B (en) 2021-01-05

Family

ID=62468068

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201711234252.0A Active CN108144592B (en) 2016-12-02 2017-11-30 Superparamagnetic composite nanoparticle, preparation method thereof and method for efficiently and selectively recovering phosphate

Country Status (2)

Country Link
CN (1) CN108144592B (en)
HK (1) HK1252256A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109133164A (en) * 2018-11-15 2019-01-04 湖北天瓷电子材料有限公司 A kind of high dispersiveness spherical titanium dioxide process
CN110586933B (en) * 2019-10-31 2021-08-31 福州大学 High-temperature-resistant modification method of zirconium dioxide coated FeCo absorbent
CN113385186A (en) * 2021-07-14 2021-09-14 南京工业大学 Novel magnetic core-shell type composite catalyst and preparation method and application thereof

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102614840A (en) * 2012-04-12 2012-08-01 南昌航空大学 Preparation method for magnetic nano material for efficiently removing phosphate radicals and nitrates

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102614840A (en) * 2012-04-12 2012-08-01 南昌航空大学 Preparation method for magnetic nano material for efficiently removing phosphate radicals and nitrates

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
"Sonochemical synthesis of magnetic core-shell Fe3O4@ZrO2 nanoparticles and their application to the highly effective immobilization of myoglobin for direct electrochemistry";Hua-Ping Peng等;《Electrochimica Acta》;20110223;第56卷;第4232页左栏第2.2节 *
"基于Fe3O4@ZrO2磁性纳米颗粒选择性富集-电感耦合等离子体发射光谱法检测蔬菜中痕量有机磷研究";巫远招等;《农药学学报》;20101231;第12卷(第2期);摘要、第180页左栏第1.3节、第1.4.6节 *
"溶剂热法制备四氧化三铁颗粒及其磁性复合颗粒制备";杨兵军;《中国优秀硕士学位论文全文数据库 工程科技I辑》;20120915(第9期);第25页第3.4节 *
巫远招等."基于Fe3O4@ZrO2磁性纳米颗粒选择性富集-电感耦合等离子体发射光谱法检测蔬菜中痕量有机磷研究".《农药学学报》.2010,第12卷(第2期),摘要、第180页左栏第1.3节、第1.4.6节. *

Also Published As

Publication number Publication date
CN108144592A (en) 2018-06-12
HK1252256A1 (en) 2019-05-24

Similar Documents

Publication Publication Date Title
Fang et al. Fabrication of silica-free superparamagnetic ZrO2@ Fe3O4 with enhanced phosphate recovery from sewage: performance and adsorption mechanism
Bao et al. Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: behaviours and mechanisms
Wang et al. Preparation and evaluation of magnetic nanoparticles impregnated chitosan beads for arsenic removal from water
Wang et al. Enhanced antimonate (Sb (V)) removal from aqueous solution by La-doped magnetic biochars
Wu et al. Magnetic Fe3O4@ CuO nanocomposite assembled on graphene oxide sheets for the enhanced removal of arsenic (III/V) from water
Cui et al. Phosphorus recovery by core-shell γ-Al2O3/Fe3O4 biochar composite from aqueous phosphate solutions
Qi et al. Synthesis of Ce (III)-doped Fe3O4 magnetic particles for efficient removal of antimony from aqueous solution
Liu et al. Multifunctional nanocomposites Fe3O4@ SiO2-EDTA for Pb (II) and Cu (II) removal from aqueous solutions
Bao et al. Highly selective removal of Zn (II) ion from hot-dip galvanizing pickling waste with amino-functionalized Fe3O4@ SiO2 magnetic nano-adsorbent
Lin et al. Removal of arsenic contaminants with magnetic γ-Fe2O3 nanoparticles
Zhang et al. Highly efficient removal of Cr (VI) from wastewater via adsorption with novel magnetic Fe3O4@ C@ MgAl-layered double-hydroxide
Idris et al. Synthesis of magnetic alginate beads based on maghemite nanoparticles for Pb (II) removal in aqueous solution
Wang et al. Lead and uranium sorptive removal from aqueous solution using magnetic and nonmagnetic fast pyrolysis rice husk biochars
Zhou et al. Removal of Cu2+ from aqueous solution by chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid
Dey et al. Cobalt ferrite nanoparticles aggregated schwertmannite: A novel adsorbent for the efficient removal of arsenic
Xiong et al. Facile synthesis of magnetic nanocomposites of cellulose@ ultrasmall iron oxide nanoparticles for water treatment
Li et al. Arsenazo-functionalized magnetic carbon composite for uranium (VI) removal from aqueous solution
Pan et al. Nanosized yolk–shell Fe3O4@ Zr (OH) x spheres for efficient removal of Pb (II) from aqueous solution
Wei et al. Magnetic separation of uranium by CoFe2O4 hollow spheres
Peng et al. One-step and acid free synthesis of γ-Fe2O3/SBA-15 for enhanced arsenic removal
Zhu et al. Hydrothermal synthesis of a magnetic adsorbent from wasted iron mud for effective removal of heavy metals from smelting wastewater
CN108144592B (en) Superparamagnetic composite nanoparticle, preparation method thereof and method for efficiently and selectively recovering phosphate
Goswami et al. Removal of fluoride from drinking water using nanomagnetite aggregated schwertmannite
Liu et al. Adsorption of phosphate ions from aqueous solutions by a CeO2 functionalized Fe3O4@ SiO2 core-shell magnetic nanomaterial
Liu et al. Synthesis and characterization of magnetic Fe 3 O 4@ CaSiO 3 composites and evaluation of their adsorption characteristics for heavy metal ions

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
REG Reference to a national code

Ref country code: HK

Ref legal event code: DE

Ref document number: 1252256

Country of ref document: HK

GR01 Patent grant
GR01 Patent grant